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| United States Patent |
6,071,223
|
|
Reider
, et al.
|
June 6, 2000
|
System for directing a leading edge of continuous form paper onto a stack
Abstract
Two movable members, one on either side of a pre-folded continuous form
entering a paper stacking area, are driven according to a determined
position of the pre-folded form to push a leading edge of the form to one
or another side of the stacking area so that the folds in the form will
develop correctly in a stack. Only one of the members is permitted to
contact the form at any time, and the members are separated by a
sufficient angle so that no position of the members permits both members
to contact the form. After directing the first and second sheets of the
form, the members return to a home position in which neither member
obstructs or interferes with subsequent stacking of the form. The position
of the pre-folded form may be determined by a leading edge sensor, by a
sheet feed rate sensor, by a fold position sensor, by a fold orientation
sensor, by timing from a predetermined position, or by manual input. When
a fold detector orientation sensor is used, the leading edge is
appropriately directed to one or another side of the stacking area
depending on the orientation of the folds detected in the form. The fold
orientation sensor may use the properties of the stiffness of the
continuous form and fold memory to detect the orientation of a fold.
| Inventors:
|
Reider; Robert J. (Longmont, CO);
Campbell; Ronald R. (Boulder, CO)
|
| Assignee:
|
Pentax Technologies Corporation (Broomfield, CO)
|
| Appl. No.:
|
969831 |
| Filed:
|
November 13, 1997 |
| Current U.S. Class: |
493/410; 493/11; 493/23; 493/24; 493/409; 493/411; 493/413 |
| Intern'l Class: |
B31F 001/08 |
| Field of Search: |
493/356,357,410,414,411,412,413,417,409,11,23,24
270/39.01,40
|
References Cited
U.S. Patent Documents
| 2906527 | Sep., 1959 | Blain.
| |
| 3187172 | Jun., 1965 | Lettan | 493/411.
|
| 3460825 | Aug., 1969 | Mets et al.
| |
| 3627304 | Dec., 1971 | Reeder et al.
| |
| 3735975 | May., 1973 | Sukel | 493/11.
|
| 4427404 | Jan., 1984 | Yamada | 493/411.
|
| 4460350 | Jul., 1984 | Mittal | 493/412.
|
| 4494948 | Jan., 1985 | Teyssier | 493/412.
|
| 4508527 | Apr., 1985 | Uno et al.
| |
| 4723488 | Feb., 1988 | Inouye | 493/411.
|
| 4751879 | Jun., 1988 | Van Pelt.
| |
| 4811688 | Mar., 1989 | Turner | 270/39.
|
| 5029828 | Jul., 1991 | Sato | 493/410.
|
| 5030192 | Jul., 1991 | Sager | 493/414.
|
| 5074836 | Dec., 1991 | Fechner et al.
| |
| 5123890 | Jun., 1992 | Green, Jr.
| |
| 5149075 | Sep., 1992 | Crowley et al.
| |
| 5242366 | Sep., 1993 | Kita.
| |
| 5255008 | Oct., 1993 | Yoshida.
| |
| 5425694 | Jun., 1995 | Negishi.
| |
| 5529564 | Jun., 1996 | Hediger | 493/357.
|
| Foreign Patent Documents |
| 52-50818 | Nov., 1977 | JP.
| |
| 54-110021 | Aug., 1979 | JP.
| |
| 55-4070 | Jan., 1980 | JP.
| |
| 55-44421 | Mar., 1980 | JP.
| |
| 55-66456 | May., 1980 | JP.
| |
| 56-21713 | May., 1981 | JP.
| |
| 56-61271 | May., 1981 | JP.
| |
| 57-98465 | Jun., 1982 | JP.
| |
| 58-3807 | Jan., 1983 | JP.
| |
| 59-7672 | Jan., 1984 | JP.
| |
| 59-7326 | Mar., 1984 | JP.
| |
| 1215558 | Dec., 1970 | GB.
| |
Other References
Pentax Active Stacking System brochure, Dec. 14, 1995.
An English Language Abstract of JP 54-110021.
An English Language Abstract of JP 55-44421.
An English Language Abstract of JP 55-66456.
An English Language Abstract of JP 56-61271.
An English Language Abstract of JP 59-7672.
|
Primary Examiner: Vo; Peter
Assistant Examiner: Calve; James P.
Attorney, Agent or Firm: Greenblum & Bernstein, P.L.C.
Claims
What is claimed is:
1. A leading edge directing system for directing the leading edge of a
pre-folded form to begin a folded stack, comprising:
a stacking platform for stacking said pre-folded form, said stacking
platform having front and rear sides;
an entry path above said stacking platform through which said pre-folded
form is introduced toward said stacking platform;
a first guide member, movably mounted along said entry path on said front
side of said stacking platform and above said stacking platform;
a second guide member, movably mounted along said entry path on said rear
side of said stacking platform and above said stacking platform;
a position determining system for defining a position of the continuous
form;
at least one motor linked to each of said first and second guide members,
for moving said first and second guide members; and
a connection between said first and second guide members for maintaining a
substantially constant separation between said first and second guide
members over an entire range of movement of said first and second guide
members, only one of said first and second guide members contacting the
continuous form at any position within said entire range of movement of
said first and second guide members; and
a controller, connected to said position determining system and said motor,
for moving both of said first and second guide members relative to one
another and depending on said position of the pre-folded form defined by
the position determining system, only one of said first and second guide
members pushing a leading edge of the pre-folded form toward one of said
front and rear sides of said stacking platform at any position within said
entire range of movement.
2. The leading edge directing system according to claim 1, wherein said
position determining system includes a position measuring system having a
leading edge sensor that detects a position of the leading edge of the
pre-folded form relative to a position of said first and second guide
members.
3. The leading edge directing system according to claim 2, wherein said
position determining system includes a timer that measures an amount of
time taken for the leading edge of the pre-folded form to travel a
predetermined distance relative to said position of said first and second
guide members.
4. The leading edge directing system according to claim 2, wherein said
position measuring system includes a form movement sensor that directly
measures a distance traveled by the pre-folded form relative to said
position of said first and second guide members.
5. The leading edge directing system according to claim 2, wherein said
position determining system includes:
a fold orientation determining system for defining an orientation of folds
in the pre-folded form.
6. The leading edge directing system according to claim 5, wherein said
fold orientation determining system includes:
a fold orientation input device for inputting a predetermined orientation
of a leading fold in the pre-folded form following the leading edge.
7. The leading edge directing system according to claim 5, wherein said
fold orientation determining system includes:
a fold orientation sensor that detects an orientation of folds in the
pre-folded form following the leading edge.
8. The leading edge directing system according to claim 7, wherein said
fold orientation sensor comprises:
at least one wall placed upstream of said entry path, said at least one
wall forming a corner that changes a direction of the continuous form and
forms a detectable clearance, depending on predetermined stiffnesses of
the continuous form and the folds, between said at least one wall and the
continuous form, an opening being formed through said at least one wall at
said corner;
a media detection sensor that senses said continuous form at said opening,
said media detection sensor being responsive to the detectable clearance
to sense the folds in the continuous form.
9. The leading edge directing system according to claim 7, for use with a
printer placed upstream along a form transport path leading through said
entry path, said leading edge directing system directing the leading edge
of a pre-folded form output by the printer to begin a folded stack,
wherein said fold orientation sensor is positioned upstream of said
printer along the form transport path.
10. The leading edge directing system according to claim 6, wherein said
position determining system includes:
a fold position determining system for defining positions of folds in the
pre-folded form relative to said position of said first and second guide
members.
11. The leading edge directing system according to claim 2, wherein each of
said first and second guide members is linked to said motor by a common
member to move in a same direction.
12. The leading edge directing system according to claim 11, wherein said
first guide member is mounted to a first rotatably supported shaft
parallel to said entry path toward said front side of said stacking
platform, and said second guide member is mounted to a second rotatably
supported shaft parallel to said entry path toward said rear side of said
stacking platform.
13. The leading edge directing system according to claim 12, wherein a
first driven gear is coaxially fixed to said first shaft and a second
driven gear is coaxially fixed to said second shaft, each of said first
driven gear and said second driven gear being driven by a common drive
gear driven by said motor.
14. The leading edge directing system according to claim 13, wherein a gear
ratio between said first and second driven gears and said common drive
gear is set such that each of said first and second driven gears rotates
by less than a full rotation for each full rotation of said common drive
gear.
15. The leading edge directing system according to claim 14, said common
driven gear and said controller being connected to a home position
detector for detecting each full rotation of said driven gear.
16. The leading edge directing system according to claim 1, wherein said
position determining system includes a position input device for inputting
a predetermined position of the pre-folded form relative to said position
of said first and second guide members.
17. The leading edge directing system according to claim 1, wherein each of
said first and second guide members is provided with a collapsible
assembly for collapsing said guide member to permit said constant
separation to be reduced at lateral ends of the entire range of movement,
each collapsible assembly comprising:
a hub acting as a base for the collapsible assembly;
a pin provided on said hub as a stop;
a guide wire for pushing said leading edge of the pre-folded form toward
said one of said front and rear sides of said stacking platform, said
guide wire rotatably mounted on said hub on an entry path side of said
pin;
a resilient biasing member that pushes said guide wire against said pin in
a same direction as said guide member pushes said leading edge, said guide
wire being collapsible away from said pin when said guide wire encounters
an obstacle along said same direction as said guide wire pushes said
leading edge.
18. The leading edge directing system according to claim 17, wherein said
collapsible assembly is rotatably mounted, and wherein said resilient
biasing member comprises a torsion spring coaxial with a center of
rotation of said collapsible assembly and of said elongated guide member.
19. The leading edge directing system according to claim 1, wherein each of
said front and rear guide members comprises at least one elongated guide
wire rotatable into said entry path to push said leading edge of the
pre-folded form toward said one of said front and rear sides of said
stacking platform.
20. The leading edge directing system according to claim 1, wherein said
controller moves both of said first and second guide members such that
only one of said first and second guide members pushes a leading edge of a
first sheet of the pre-folded form toward one of said front and rear sides
of said stacking platform according to said position of the pre-folded
form defined by the position determining system, and subsequently moves
both of said first and second guide members such that a remaining one of
said first and second guide members pushes a leading edge of a second
sheet of the pre-folded form toward a remaining one of said front and rear
sides of said stacking platform according to said position of the
pre-folded form defined by the position determining system.
21. The leading edge directing system according to claim 1, wherein said
controller moves both of said first and second guide members such that
only one of said first and second guide members pushes a leading edge of a
first sheet of the pre-folded form toward one of said front and rear sides
of said stacking platform according to said position of the pre-folded
form defined by the position determining system, then moves both of said
first and second guide members such that a remaining one of said first and
second guide members pushes a leading edge of a second sheet of the
pre-folded form toward a remaining one of said front and rear sides of
said stacking platform according to said position of the pre-folded form
defined by the position determining system; then returns both of said
first and second guide members to a home position in which neither of said
first and second guide members interfere with subsequent stacking of said
continuous form.
22. A leading edge directing system for directing the leading edge of a
pre-folded form to begin a folded stack, comprising:
a stacking platform for stacking said pre-folded form, said stacking
platform having front and rear sides;
an entry path above said stacking platform through which said pre-folded
form is introduced toward said stacking platform;
a first guide member, movably mounted along said entry path on said front
side of said stacking platform and above said stacking platform;
a second guide member, movably mounted along said entry path on said rear
side of said stacking platform and above said stacking platform;
a position determining system for defining a position of the continuous
form;
a motor linked to each of said first and second guide members, for moving
said first and second guide members so that only one of said first and
second guide members may contact the continuous form at any position of
said first and second guide members; and
a controller, connected to said position determining system and said motor,
for moving both of said first and second guide members such that only one
of said first and second guide members pushes a leading edge of the
pre-folded form toward one of said front and rear sides of said stacking
platform, according to said position of the pre-folded form defined by the
position determining system;
wherein said motor is linked to each of said first and second guide members
by a transmission mechanism that maintains an angle of 30 to 100 degrees
between said first and second guide members at any position of said first
and second guide members so that only one of said first and second guide
members may contact the continuous form at any position of said first and
second guide members.
23. The leading edge directing system according to claim 22, wherein said
transmission mechanism maintains an angle of 45 to 90 degrees between said
first and second guide members at any position of said first and second
guide members.
24. The leading edge directing system according to claim 23, wherein said
transmission mechanism maintains an angle of approximately 90 degrees
between said first and second guide members at any position of said first
and second guide members.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system and mechanism for directing the
leading edge of a continuous form onto a stack, and more particularly, to
a device for appropriately directing the leading sheet(s) of a continuous
form to begin a stack of forms.
2. Description of Background Information
Refolding and stacking of pre-folded continuous form paper is accomplished
either by passive (gravity fed) stackers or by active stacking systems.
Passive stackers may use a wire basket (or other box-shaped configuration)
in combination with fixed guides. Active stackers use various devices
positioned alongside the stacking platform, such as rotating paddles or
air jets, to ensure that a stack of continuous form paper stacks
correctly. However, laying the first few sheets of a stack is problematic
with both passive and active stackers, since both kinds of stackers have
no facility for appropriately placing the leading edge depending on the
fold orientations encountered such that subsequent folds will develop
correctly.
For example, with fan-fold continuous forms of paper or label stock, even
after unfolding for printing, folds tend to remain in the continuous form
in their original direction or orientation ("fold memory"), alternating
between outside folds and inside folds between sheets. In this context, an
"outside" fold is one that enters the printer with the fold cusp pointing
upward, and an "inside" fold is one that enters the printer with the fold
cusp pointing downward. Depending where the last discrete sheet of the
form is separated, a leading fold following the leading edge of the form
(usually formed at a perforation between sheets) may have either of an
outside or inside orientation. Accordingly, a leading fold following the
leading edge has a fold cusp pointing up ("outside") or down ("inside").
If the first sheet arriving at the stacking platform arrives such that
second sheet folds over in the same direction of the fold memory of the
leading fold, subsequent folding of the continuous form will encounter
only a small chance of misfolding. However, if the first sheet arriving at
the stacking platform arrives such that second sheet folds over against
the direction of the fold memory of the leading fold, then all subsequent
folds will be folded against the original fold orientation or "fold
memory," and misfolding and mis-stacking of the continuous form media will
likely occur.
Further, in a laser printer using pre-folded continuous forms, mis-stacking
and misfolding often occurs when the toner-fusing or fixing rollers "iron"
out the existing folds at the perforations between sheets of the
continuous form. As a result, the form folds lose a portion of "fold
memory," and tend not to refold easily into a stack. With high speed
printers, misfolding and mis-stacking is further exacerbated.
Even when a passive or active stacker may reliably stack a continuous form
when a group of initial sheets is properly laid down and folded, an
operator must manually lay the first sheet. If sheet feeding is automatic,
the operator must still ensure that the leading sheet is in the proper
orientation for which the stacker is designed, and may be forced to remove
the continuous form media, rotate the media input stack, and replace the
media in the printer to orient the leading sheet properly.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a leading edge
directing system that appropriately directs leading sheets of a pre-folded
continuous form so that all subsequent folding onto a stack develops
correctly.
It is a further object of the invention to provide a leading edge directing
system capable of directing leading sheets of a continuous form for any
orientation of the folds in the pre-folded continuous form.
It is a further object of the invention to provide a fold sensor, and
leading edge directing system incorporating the fold sensor, capable of
detecting fold orientation in pre-folded or fanfold continuous forms.
The above objects are attained by providing a leading edge directing system
for directing the leading edge of a pre-folded form to begin a folded
stack in which a controller, connected to a position determining system
and a motor, moves both of first and second guide members such that only
one of the guide members pushes a leading edge of the pre-folded form
toward a front or rear side of a stacking platform according to the
position of the pre-folded form as defined by a position determining
system. The guide members are movably mounted on either side of an entry
path above the stacking platform through which the pre-folded form is
introduced toward the stacking platform. The position determining system
defines a position of the continuous form. The motor is linked to each of
the guide members, and moves the guide members so that only one of the
guide members may contact the continuous form at any position of the guide
members.
The position determining system may include a leading edge sensor that
detects a position of the leading edge of the pre-folded form relative to
the guide members. In addition to the leading edge sensor, the position
determining system may include a timer that measures the time taken for
the leading edge of the pre-folded form to travel a predetermined distance
relative to the guide members; or a form movement sensor that directly
measures a distance traveled by the pre-folded form relative to the guide
members; or a position input device for inputting a predetermined position
of the pre-folded form relative to the guide members. Further, in addition
to the leading edge system, the position determining system may include a
fold orientation determining system for defining an orientation of folds
in the pre-folded form, which may have a fold orientation input device for
inputting a predetermined orientation of a leading fold in the pre-folded
form following the leading edge; or a fold orientation sensor that detects
an orientation of folds in the pre-folded form following the leading edge;
or a fold position determining system for defining positions of folds in
the pre-folded form relative to the guide members
Preferably, the fold orientation sensor includes one or more walls placed
along the transport path, the wall or walls forming a corner that changes
a direction of the continuous form and forms a detectable clearance
between a wall or walls and the continuous form. The clearance depends on
predetermined stiffnesses of the continuous form and the folds. An opening
is formed through the wall at the corner, and a media detection sensor,
responsive to the detectable clearance to sense the folds in the
continuous form, senses the continuous form at the opening.
If a fold orientation sensor is provided, it may be associated with a
printer placed upstream along a form transport path leading through the
entry path, where the leading edge directing system directs the leading
edge of a pre-folded form output by the printer to begin a folded stack.
The fold orientation sensor may be positioned upstream of the printer or
within the printer along the form transport path.
In this manner, the leading edge directing system can conduct combinations
of operations in which the position or orientation of the folds or leading
edge are detected, set manually by an operator, or determined. The
positions may be determined according to a timer from a known position, or
according to direct measurement of the advance of the continuous form or
the feeding device. The continuous form may also be set in a predetermined
position.
The guide members may be linked to the motor by a common member to move in
the same direction. In this case, the guide members may be mounted to
rotatably supported shafts parallel to and on either side of to the entry
path. The shafts may be driven by a common drive gear driven by the motor,
and the gear ratio between the driven gears and the common drive gear may
be set such that the driven gears rotate by less than a full rotation for
each full rotation of the common drive gear. The common driven gear and
the controller may be connected to a home position detector for detecting
each full rotation of the driven gear.
The guide members may be provided with a collapsible assembly including a
pin; a guide wire for pushing the leading edge of the pre-folded form
toward the one of the front and rear sides of the stacking platform; and a
resilient biasing member that pushes the guide wire against the pin in the
same direction as the guide wire pushes the leading edge. In this manner,
the guide wire is collapsible, away from the pin, when the guide wire
encounters an obstacle along the same direction as the guide wire pushes
the leading edge. Preferably, the collapsible assembly is rotatably
mounted, and the resilient biasing member includes a torsion spring
coaxial with a center of rotation of the collapsible assembly.
Preferably, each of the front and rear guide members includes one or more
elongated guide wires rotatable into the entry path to push the leading
edge of the pre-folded form toward the one of the front and rear sides of
the stacking platform.
The motor is preferably linked to each of the first and second guide
members by a transmission mechanism that maintains an angle of 30 to 100
degrees between the members at any position, so that only one of the guide
members may contact the continuous form at any position of the guide
members. The angle is more preferably 45 to 90 degrees, and ideally
approximately 90 degrees. Below 45 degrees, and even more so below 30
degrees, during operation, there is an increased chance that the wire
guide on the non-contacting side will contact or interfere with the sheet.
Above 90 degrees, and even more so above 100 degrees, the mechanical
design becomes cumbersome. At approximately 90 degrees, smooth operation,
with each wire guide moved out of the way when not needed, is ensured.
In one modification of the system, according to the form position defined
by the position determining system, the controller moves the guide members
such that only one of the guide members pushes the leading edge of a first
sheet of the form toward a side of the stacking platform, and subsequently
moves the guide members such that the remaining guide member pushes the
leading edge of the second sheet toward the remaining side of the stacking
platform. In another, the controller subsequently returns the guide
members to a home position in which neither guide member interferes with
subsequent stacking of the continuous form.
In another aspect of the invention, a fold detector detects folds in a
pre-folded continuous form moving along a transport path. The fold
detector includes one or more walls placed along the transport path, the
wall or walls forming a corner that changes a direction of the continuous
form and forms a detectable clearance between a wall or walls and the
continuous form. The clearance depends on predetermined stiffnesses of the
continuous form and the folds. An opening is formed through the wall at
the corner, and a media detection sensor, responsive to the detectable
clearance to sense the folds in the continuous form, senses the continuous
form at the opening.
In one version of this aspect of the invention, two substantially straight
walls intersect to form an angled corner that changes a direction of the
continuous form, so that when no detectable fold is at the angled corner,
the detectable clearance forms between one of the substantially straight
walls and the continuous form. When a detectable fold is at the angled
corner, the detectable clearance reduces, and the media detection sensor
is responsive to the reducing of the detectable clearance to sense the
folds in the continuous form.
In this case, the media detection sensor may include a limit switch having
a movable lever emerging from the opening at the one of the substantially
straight walls, so that the movable lever is depressed and the limit
switch activated when the detectable clearance is reduced. Conversely, the
movable lever is released and the limit switch deactivated when the
detectable clearance is formed. Preferably, the two substantially straight
walls intersect at a right angle to form a right angle corner, and the
wall having the opening is vertical, the remaining wall being horizontal.
In another version of this aspect of the invention, an arcuate wall forms
an arcuate corner that changes a direction of the continuous form when a
detectable fold is at the arcuate corner, so that the detectable clearance
forms between the arcuate corner and the continuous form. When no
detectable fold is at the arcuate corner, the detectable clearance is
reduced, and the media detection sensor is responsive to the forming of
the detectable clearance to sense the folds in the continuous form.
Preferably, the arcuate wall curves from a horizontal direction to a
vertical direction.
The media detection sensor may include a proximity switch directed through
the opening, so that when the detectable clearance is formed, the
proximity switch is deactivated, and when the detectable clearance is
reduced, the proximity switch is activated.
In still another aspect of the invention, a leading edge directing system
directs the leading edge of a pre-folded form (having folds formed
therein) moving along a transport path to begin a folded stack. A
controller, connected to a media detection sensor and a motor, moves guide
members such that, depending on the positions of folds detected by the
media detection sensor, the guide members push a leading edge of the
pre-folded form toward one of front and rear sides of the stacking
platform. The pre-folded form is introduced toward the stacking platform
through an entry path above the stacking platform. The guide members are
movably mounted along the entry path on either side of the stacking
platform and above the stacking platform, and the motor is linked to and
moves the guide members. A fold detection corner that changes a direction
of the continuous form is located at a predetermined position, upstream of
the entry path and along the transport path. The fold detection corner
forms a detectable clearance between itself and the continuous form, and
the media detection sensor is responsive to the detectable clearance to
detect the positions of the folds in the continuous form.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further explained in the description that follows
with reference to the drawings, illustrating, by way of non-limiting
examples, various embodiments of the invention, with like reference
numerals representing similar parts throughout the several views, and in
which:
FIG. 1 is a schematic side view of a first embodiment of the leading edge
directing system according to the present invention;
FIG. 2 is a perspective view of a leading edge directing mechanism of the
leading edge directing system shown in FIG. 1;
FIG. 3 is a side view of the leading edge directing mechanism shown in FIG.
2;
FIG. 4 is a front view of the leading edge directing mechanism shown in
FIGS. 2 and 3;
FIG. 5 is a block diagram of a control circuit for controlling the
embodiments of the leading edge directing system according to the present
invention;
FIG. 6 is a timing chart showing one application of a control timing for
controlling the lead edge directing system according to the invention;
FIG. 7 shows a first position of a continuous form and leading edge
directing mechanism according to the invention;
FIG. 8A shows a second position of a continuous form and leading edge
directing mechanism according to the invention;
FIG. 8B is a variation of the mechanism shown in FIG. 8A;
FIG. 9 shows a third position of a continuous form and leading edge
directing mechanism according to the invention;
FIGS. 10A and 10B show a flowchart of a routine for controlling the leading
edge directing system according to the present invention;
FIG. 11 is a flowchart of a routine in which delays and intervals are
adjusted dynamically in response to changing sheet feed rates;
FIG. 12 is a schematic side view of a second embodiment of the leading edge
directing system according to the present invention, in which a
perforation/fold detector is placed within a printer;
FIGS. 13A and 13B show side schematic views of a first embodiment of a fold
sensor for detecting an orientation of a fold in a continuous form at two
positions of the continuous form;
FIGS. 14A and 14B show detailed side views of the fold sensor of FIGS. 13A
and 14A, respectively;
FIGS. 15A and 15B show side schematic views of a second embodiment of a
fold sensor for detecting an orientation of a fold in a continuous form at
two positions of the continuous form;
FIGS. 16A and 16B show detailed side views of the fold sensor of FIGS. 15A
and 15A, respectively; and
FIGS. 17A and 17B show signals generated by the fold sensor of FIGS. 16A
and 16B, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a schematic view of the leading edge directing system according
to the invention, the system operating with a continuous form printer 72.
Referring to FIG. 1, the printer 72 and leading edge directing system 100
are directly supported on a base 10. Alternatively, the printer 72 may be
supported by its own support structure. The base 10 includes a vertical
support 16, which supports the continuous form printer 72.
The continuous form printer 72 is preferably a conventional
electrophotographic continuous form printer, including a sheet feeding
device and a printing device, the printer 72 accepting and printing upon
pre-folded continuous form paper (fan fold paper, label stock, and the
like). As shown in FIG. 1, the continuous form printer 72 discharges the
continuous form paper into the leading edge directing system 100. Once the
leading edge of the initial sheet(s) of the pre-folded continuous form has
been appropriately directed by the leading edge directing system as
described below, subsequent stacking may be performed with the assistance
of an active stacking mechanism 76.
The leading edge directing system 100 includes a leading edge directing
mechanism incorporating a rotatable guide assembly 20, which directs the
leading edge of a pre-folded continuous form in an appropriate direction
for correct stacking. As shown in FIGS. 1-4, the rotatable guide assembly
20 preferably includes a front guide wire 28F (driven by a front driven
gear 24F) and a rear wire gear 28R (driven by a rear driven gear 24R) as
first and second guide members for pushing a leading edge of the
pre-folded form toward the front and rear sides of the stacking area. Each
of the driven gears 24R, 24F engages and is driven by a common drive gear
22b, which is in turn driven by a reversible motor 22.
FIG. 2 is a perspective view of an embodiment of the leading edge directing
mechanism shown in FIG. 1. As shown in FIGS. 2 through 4, the rotatable
guide assembly 20 is supported by a housing 12, which is in turn supported
by the vertical support 16. The front driven gear 24F is coaxially fixed
to a front (first) driven shaft 25F that is in turn supported by bearing
supports 25a secured to the housing 12 at either end. Similarly, the rear
driven gear 24R is coaxially fixed to a rear (second) driven shaft 25R,
which is supported by bearing supports 25a secured to the housing 12 at
either end. Each of the guide wires 28F and 28R of the rotatable guide
assembly 20 is supported by its respective driven shaft 25F, 25R.
The front and rear driven shafts 25F and 25R are spaced to bracket the
continuous form path, forming an entry path to the stacking area (i.e., a
horizontal stacking support assembly 14 or stacking platform)
therebetween. Accordingly, each of the rotatable guide wires 28F and 28R
may operate on one side of the continuous form. Furthermore, with this
arrangement, neither of the shafts 25F nor 25R interferes with the form
transport path or entry path, and the rotatable guide wires 28F and 28R
only interfere with the transport path or entry path when one is swung
into the transport path to direct the pre-folded continuous form
appropriately.
Each of the driven gears 24F and 24R engages the common drive gear 22b,
which (as shown in FIGS. 2-4) is driven by the (reversible) guide wire
motor 22 via a drive shaft 22a. The drive motor 22 is affixed to the
housing 12. The drive ratio between the drive gear 22b and the driven
gears 24F, 24R is arranged such that the driven gears 24F, 24R rotate by
less than one full rotation for each rotation of the drive gear 22b. One
preferable gear ratio is 4:1, so that each driven gear rotates by
90.degree. for each full rotation of the drive gear 22b. Transmission of
driving force to the rotatable guide wires 28F, 28R may be alternatively
accomplished by other mechanical drives, for example, a four-bar linkage,
eccentric gears, planetary gears, solenoids, etc.
The front and rear rotatable guide wires 28F and 28R are separated by a
sufficient angular separation such that only one may contact the
continuous form at a time, given that the continuous form fluctuates in
position to the front and rear after being guided into the entry path. The
guide wires 28F and 28R are so arranged because if guide members on both
sides of a continuous form are permitted to contact the form, timing for
controlling the guide members must be exact. Furthermore, no matter how
well the timing is executed if guide members on both sides of the form are
permitted to contact the form, if forms having different characteristics
(i.e., thickness, rigidity, length) are introduced into the system, jams
and stacking errors are likely to occur. Since the present device is
arranged such that only one guide wire contacts the form at a time, such
problems are not present.
In FIGS. 2-4, the angle at which the directions of the front and rear
rotatable guide wires 28F and 28R intersect in the home position is
arranged so that, upon any rotation of the guide wires 28F and 28R, no
position of the front and rear wire guides 28F and 28R allows the
continuous form to contact both wire guides 28F and 28R. As shown in FIGS.
2-4, the angle is preferably 30-100.degree.. Below 30.degree., during
operation, there is an increased chance that the wire guide on the
non-contacting side (28F or 28R) will contact or interfere with the sheet.
Above 100.degree., the mechanical design becomes cumbersome, as the motor
22 increases in size to move the wire guides 28F, 28R more quickly, the
shafts 25F, 25R must be farther apart, and the size of the gears 22b or
24F/24R may become impractical. The range is more preferably
45-90.degree., for the same reasons. The range is ideally approximately
90.degree., ensuring the most smooth operation and that each wire guide
28F or 28R is moved out of the way when not needed. In this context,
"approximately 90.degree." is defined such that the guide wires 28F, 28R
may by separated by more or less than 90 degrees, but only one may contact
the form at any time.
An encoder 52 is coaxially affixed to the drive shaft 22a, and a position
sensor 54 supported by the housing 12 senses at least one position of the
encoder 52. The home position sensor 54 may be, e.g., an LED and
phototransistor combination, or a photointerruptor or magnetic sensor.
Preferably, the position sensor 54 detects at least a home position of the
rotatable wire guides, 28F and 28R, i.e., a position at which neither of
the rotatable guide wires 28F nor 28R is rotated into the form transport
path (as shown in FIGS. 2-4).
Each of the rotatable guide wires 28F, 28R is provided with a collapsible
assembly 26. As shown in FIG. 4, the collapsible assembly 26 includes a
drive lug 26a, a drive pin 26b, a torsion spring 26c as a resilient
biasing member, and a torsion support bushing 26d. The drive lug 26a is
fixed to the rotatable driven shaft 25F via a set screw 26e. The drive pin
26b protrudes from the drive lug 26a beside the front guide wire 28F (a
guide member of the collapsible assembly 26) on the opposite side of the
front guide wire 28F to transport the paper path. The front guide wire 28F
is fixed to a bushing 26f that is rotatably mounted with respect to the
driven shaft 25F. Further, the torsion support bushing 26d is fixed to the
driven shaft 25F via a set screw 26g to rotate therewith. A torsion spring
26c (coaxial with the center of rotation of the collapsible assembly 26)
links the bushing 26f and the torsion support bushing 26d, resiliently
biasing the bushing 26f (and accompanying front guide wire 28F) in the
direction of the drive pin 26b.
Accordingly, the torsion spring 26c pushes the front wire guide 28F against
the drive pin 26b in the same direction as the front guide wire 28F pushes
the leading edge of the pre-folded continuous form 74. The front guide
wire 28F (guide member) is collapsible away from the drive pin 26b when
the front wire guide 28F encounters an obstacle along the same direction
as the front wire guide 28F pushes the leading edge of the pre-folded
continuous form. That is, if the rotatable driven shaft 25F is rotated in
the direction away from the continuous form 74 along the transport path,
and the front guide wire 28F encounters an obstacle (or stopper), the
drive lug 26a and drive pin 26b, as well as the torsion support bushing
26d, may continue to rotate. However, here, the front guide wire 28F is
stopped by the obstacle or stopper, and is held in position by the torsion
spring 26c. As shown in FIG. 4 by dashed lines, a plurality of front guide
wires 28', and accompanying collapsible assemblies 26', may be provided
along the length of the front driven shaft 25F.
The rear rotatable guide wire 28R is provided with a collapsible assembly
26 similarly formed to that of the front guide wire 28F, and the
description of the collapsible assembly 26 for the rear guide wire 28R is
accordingly omitted. Similarly, the rear driven shaft 25R may be provided
with a plurality of rear guide wires 28' and collapsible assemblies 26'
along the length of the rear driven shaft 25R.
Each of the guide wires 28F, 28R is formed of a rigid wire having
sufficient strength to direct the weight of at least a full sheet of the
continuous form 74 in the appropriate direction (for example, 0.02-0.05
inch diameter wire, and preferably 0.031 inch diameter spring steel).
Wires are advantageous over thicker members or plates because they are
cheaper, have lower rotational inertia allowing rapid movement to the
target position, and have low noise in operation. If more than one wire is
provided along the length of the shafts 25F, 25R, thinner wires may be
used.
Although the rotatable guide assembly 20 may operate together with, for
example, fixed guides, the leading edge directing system 100 also
preferably includes a paper drive roller mechanism 40. The paper drive
roller mechanism 40 includes a drive roller 42 and a pressure roller 44,
which form a roller nip through which the continuous form 74 may be
driven. Front guide rod 32a and rear guide rods 32c guide the pre-folded
continuous form 74 into the roller nip between the drive roller 42 and
pressure roller 44. Each of the drive roller mechanism 40 and rotatable
guide assembly 20 are supported by the housing 12, which is in turn
supported by the vertical support 16. As shown in FIG. 2, two coaxial
drive rollers 42 of the drive roller mechanism 40 are supported by the
housing 12, via a drive roller shaft 42a and drive roller bushings 42b.
As shown in FIG. 4, the drive rollers 42 are driven by a drive roller motor
46 supported on the housing 12. The pressure roller 44 is supported at
either end by pressure roller brackets 44a (shown in FIGS. 3 and 4). The
pressure roller brackets 44a are swingable together with a wire guide 32,
the wire guide 32 including the front guide rod 32a and the rear guide
rods 32c. The wire guide 32 also includes a peripheral rod 32b, which is
rotatably mounted in the housing 12. Accordingly, the wire guide 32 is
swingable with respect to the housing 12, and may be pivoted to swing the
pressure roller 44 toward and away from the drive roller 42.
As shown in FIGS. 2-4, a horizontal stacking support assembly 14 (paper
stacking table) is provided below the rotatable guide assembly 20. A
center rib 14b is provided in the center of the horizontal stacking
support assembly 14 to push the center of a stack of forms upward, thereby
ensuring that a stack does not become thicker at the front or rear end
than in the center. A front stacking guide 18 retains stacked paper at the
front of the horizontal stacking supporting assembly 14, and is fixed to
the base 10. A stopper 17 is affixed to the front stacking guide 18 to
limit the movement of the front guide wire 28F (in cooperation with the
collapsible assemblies 26, as previously described). A rear stacking guide
19 is provided to the rear of the horizontal stacking assembly, and is
movable in the front and rear directions to hold various sizes of sheet
for the continuous form 74. The rear stacking guide 19 is supported by a
hanger rod 19a in hanger slots 12b formed in the housing 12. The slots 12b
are formed at different positions in the front and rear directions, so
that the position of the rear stacking guide 19 may be adjusted by moving
the hanger rod 19a (extending between the guide hanger slots 12b in the
housing 12) between the different slots 12b.
FIG. 5 is a block diagram describing a control system for the leading edge
directing system 100. To direct the leading edge of the form properly, the
control system must be able to find the position of the form along the
feeding path from the printer 72 to the leading edge directing system,
relative to the front and rear rotatable guide wires 28F and 28R.
Determining the position may be accomplished in several ways. Initially,
the position of the leading edge of the form must be set or detected.
However, once the position of the leading edge of the form is set or
detected, the progress of the form may be measured by a timer used with a
known paper feed speed, a form movement sensor that directly measures the
progress of the form, or a combination of both. FIG. 5 shows a block
diagram in which each candidate determining/sensing device is applied.
As shown in FIG. 5, a controller 56 for controlling the leading edge
directing system 100 includes a memory 56c, a counter 56a, and a timer
56b. The counter 56a may be used to count paper feed pulses representing a
known or measured feeding amount (described later), and the timer 56b may
be used to time intervals according to a known paper feed speed as the
pre-folded continuous form is fed. A top of form (TOF) sensor 58
(preferably provided in the printer 72, but which may be positioned
anywhere along the paper feed path) is connected to the controller 56 via
an appropriate interface. The top of form (TOF) sensor 58 detects a
leading edge of a continuous form as the form passes along the transport
path (preferably within the printer 72). In combination with the memory
56c, counter 56a, and timer 56b, and given a known or measured paper
feeding speed, the TOF sensor 58 may act as a portion of a position
determining system that detects a position of the leading edge of the
pre-folded form relative to the feeding path and the front and rear
rotatable guide wires 28F and 28R.
A perforation/fold sensor 57 is also connected to the controller 56 via an
appropriate interface. The perforation/fold sensor 57 is preferably
situated upstream of the printer, i.e., before the continuous form enters
the printer 72. In this manner, the perforation fold sensor 57 may sense
the folds of the continuous form before the folds are "ironed out" by the
fusing/fixing rollers of the electrophotographic printer 72. However, the
perforation/fold sensor 57 may also be placed at any location along the
form transport path, even within the printer 72 itself (as shown in FIG.
12). The perforation/fold sensor 57 may be a proximity sensor, a limit
switch, a photointerruptor, a reflective sensor, or any other sensor
capable of detecting the orientation of a fold (as described with
reference to FIGS. 13A-17B). In combination with the counter 56a, memory
56c, and/or the timer 56b, the perforation/fold sensor 57 acts as a
portion of a fold orientation determining system that defines an
orientation of folds in the pre-folded form, and as a portion of a fold
position determining system for defining positions of folds in the
pre-folded form relative to the position of the front and rear rotatable
guide wires 28F, 28R. Suitable fold sensors (60, 60') suitable for use as
the perforation/fold sensor 57 are described below with reference to FIGS.
13A through 17B.
A PFS encoder sensor 59 is connected to a tractor or driving device within
the printer 72 and detects forward advance of a continuous form 74. In a
preferred embodiment, the PFS encoder sensor 59 counts 1/6" advances and
generates a pulse for each 1/6" advance of the continuous form. In
combination with the TOF sensor 58, counter 56a, timer 56b, and/or memory
56c, the PFS encoder sensor 59 acts as a form movement sensor that
directly measures the distance traveled by the pre-folded form.
In the leading edge directing mechanism 20, a position sensor 54 connected
to the controller 56 senses the position of the encoder wheel 52 and drive
gear 22b via a notch 52a (shown in FIGS. 7-9) formed in the encoder wheel
52. Some of the described sensors are also shown in the schematic view of
FIG. 1, according to preferred locations.
An up/down switch 55a is also connected to the controller 56, as is a
confirmation switch 55b. The up/down switch 55a may be used to enter a
leading fold orientation to the controller 56 (for example, in case the
folds in the pre-folded form are difficult to detect). Accordingly, the
up/down switch 55a acts as a fold orientation input device for entering a
predetermined orientation in the pre-folded form following the leading
edge. The confirmation switch 55b may be used to confirm a predetermined
position of the pre-folded form 74 or leading fold along the sheet feeding
path. Accordingly, the confirmation switch 55b acts as a position input
device for entering a predetermined position of the pre-folded form 74 or
leading fold relative to the position of the front and rear rotatable
guide wires 28F and 28R.
A motor controller 21 is connected to the controller 56, and is driven by
the controller 56 to drive the reversible motor 22 in forward and reverse
directions. A drive roller motor controller 46a controls the drive roller
motor 46 and is connected to the controller 56 such that the controller 56
may start and stop the drive roller motor 56. A stacker motor controller
65 may also be connected to the controller 56, for controlling the active
stacking mechanism 76 (shown in FIG. 1) that, for example, pushes down the
front and rear edges of the continuous form as the form stacks in the
stacking area (horizontal stacking support assembly 19).
FIG. 6 is a control/timing chart representing a control routine carried out
to move the front and rear rotatable guide wires 28F and 28R to place the
first and second sheets of the continuous form in appropriate positions,
and to return the rotatable guide wires 28F and 28R to their home
positions when the first two sheets (and leading fold) are so placed. In
particular, FIG. 6 represents exemplary timing generated when the first
detected fold is an "outside" fold. The timing chart of FIG. 6 and the
flow chart of FIGS. 10A and 10B (described later) each represent a control
routine in which a combination of a direct position detector (TOF), a
direct form advance detector (PFS6), a timer (e.g., timer 56b), and a fold
detector (PERF) are used to carry out appropriate timing.
The control routine shown in FIG. 6, and in the flowchart of FIGS. 10A and
10B, is arranged for a sheet length of 11 inches, in which the top of form
(TOF) sensor 58 is approximately 15-17 inches (in practice, approximately
151/2 inches) downstream of the perforation/fold sensor 57, and in which
the leading edge directing mechanism is approximately 17 inches downstream
of the top of form (TOF) sensor 58. Accordingly, the tips of the guide
wires 28F, 28R are approximately 23-27 inches downstream of the TOF sensor
58. The measurements are taken along the transport path of the continuous
form 74, which curves in certain portions, i.e., between the
perforation/fold sensor 28 and the printer 72, or between the printer 72
and the leading edge directing mechanism 20.
In this configuration, the leading fold of the sheet following the leading
edge is placed between the top of form (TOF) sensor 58 and the
perforation/fold sensor 57 before the routines of FIGS. 6, 10A and 10B are
carried out. Accordingly, the first detectable fold is actually the second
fold following the leading edge of the continuous form. In this context,
when discussing the order of folds, a (first, second, etc., "outside" or
"inside") "detectable" fold is one that passes the perforation/fold sensor
58 and may be detected by the perforation/fold sensor 58, and a (first,
second, etc., "outside" or "inside") fold not identified as "detectable"
is in absolute order from the leading edge of the continuous form.
A rate of sheet transport of approximately 41/2 inches/second (about 24
sheets of the form per minute) is used. When the continuous form is placed
or arrives along the transport path with the leading edge at the TOF
sensor 58, the first detectable fold is encountered approximately 51/2
inches after the form begins to feed (allowing for variations in the
curved feeding path). Accordingly, the first detectable fold (the second
fold) is detectable at approximately 33 pulses (6 pulses/inch*51/2
inches.apprxeq.33), the second detectable fold (the third fold) is
detectable at approximately at 99 pulses (6 pulses/inch*11 inches+33
pulses.apprxeq.99), and the rotatable guide motor 22 is first started at
approximately 15-16 inches (31/2 seconds*41/2 inches/second=15-16) after
the top of form (TOF) sensor 58 detects the leading edge of the form 74.
However, it should be noted that the pulse counts may be adjusted for a
particular length of sheet, and the delays and timing adjusted for a
particular feed rate. Moreover, if the feed rate changes for any reason,
e.g., if the printer 72 prints a page having a large image or graphic
requiring significant processing, the delays and timing may be adjusted to
compensate (e.g., by monitoring the PFS sensor 59, as shown in FIG. 11).
For example, similar calculations to those above, with appropriate delays
and intervals for form size, feed rate, transport path distances, etc.,
may be performed in the compensating routine shown in FIG. 11.
In FIG. 6, TOF is the top of form signal from the top of form sensor 58;
PFS6 is the PFS signal from the paper feed sensor 59; PERF is the
perforation/fold signal from the perforation/fold sensor 57; HSC
represents critical periods when the PFS counter (for example, counter
56a) is monitored by the controller; MOTOR CW represents a clockwise
signal sent to the rotatable guide motor controller 21 for driving the
drive gear 22b in the clockwise direction from the perspective of FIG. 9
(i.e., to move the rotatable guides 28F and 28R from the home position
shown in FIG. 7 toward the position shown in FIG. 8A, or to return to the
home position shown in FIG. 7 from the position shown in FIG. 9). MOTOR
CCW is a similar signal for the counterclockwise direction from the
perspective of FIG. 1 (i.e., to move the rotatable guides 28F and 28R from
the home position shown in FIG. 7 toward the position shown in FIG. 9, or
to return to the home position shown in FIG. 7 from the position shown in
FIG. 8A). HOME is a signal from the position sensor 54 upon detection of
the home position of the encoder wheel 52, drive gear 22b, and front and
rear rotatable guides 28F and 28R. ERROR represents an error (if generated
at step S112), which may end the process when no folds or two subsequent
outside folds "O" are detected.
FIGS. 7-9 show various positions of the leading edge directing mechanism 20
according to the invention, which may be generated by the control routine
shown in FIGS. 6, 10A, and 10B. In particular, FIGS. 7, 8A, and 9
represent exemplary positions generated when the leading fold is an
"inside" fold (i.e., the first detectable fold is an "outside" fold). FIG.
7 shows a home or neutral position where neither of the rotatable guide
wires 28F nor 28R is positioned to guide or interference with the
continuous form 74 being fed along the transport path, and each guide 28F
and 28R is in a position rotated away from the continuous form 74. FIG. 8A
depicts a first variation of the embodiment of a leading edge directing
mechanism, in which the front rotatable guide wire 28F directs the leading
edge of a continuous form 74 toward the rear of the paper stacking area
(horizontal stacking support assembly 14). In FIG. 8A, the rear rotatable
guide wire 28R is moved away from the continuous form 74 by the
simultaneous rotation of the front and rear driven gears 24F, 24R, as
driven by the common drive gear 22b.
FIG. 8B shows a second variation of the embodiment shown in FIG. 8A, in
which the front guide wire 28F may guide the continuous form 74 toward the
rear of the paper stacking area (horizontal stacking support assembly 14).
The variation in FIG. 8B is useful when one or more portions of the
stacking system obstruct the free movement of the front and rear rotatable
guide wires 28F, 28R. In contrast to FIG. 8A, in the variation shown in
FIG. 8B, the stopper 17 (also shown in FIGS. 2 through 5) arrests the
rotating motion of the rear guide wire 28R. A similar stopper 17 may be
positioned to arrest the rotating motion of the front guide wire 28F. As
previously described, a collapsible assembly 26 (front or rear) operates
such that the drive pin 26b and drive lug 26a continue to rotate when the
motion of the corresponding guide wire 28R (28F) is arrested, as the rear
driven gear 24R is rotated simultaneously with the front driven gear 24F.
As shown in FIG. 8B, when the motion of the wire guide is arrested, the
torsion spring 26c keeps the guide wire 28R (28F) biased against the
stopper 17, until the drive lug 26a and drive pin 26b return from the
position shown in FIG. 8B when the rear guide wire 28R (28F) is driven
back toward the home position shown in FIG. 7.
FIG. 9 shows a position in which the rear guide wire 28R is directed toward
the front of the horizontal stacking support assembly 14, directing a
second sheet of the continuous form 74, so that the leading fold of the
continuous form is appropriately directed to fold toward the front of the
stacking area. As shown in FIG. 9, simultaneously, the front guide wire
28F is rotated away from the continuous form 74 by the simultaneous
rotation of the driven gear 24F with the driven gear 24R.
As shown in FIG. 6, when the top of form (TOF) signal is detected, the PFS
counter (represented by HSC in FIG. 6) begins counting PFS pulse signals
(represented by PFS6). At this point, the rotatable guide wires 28F, 28R
are in the position shown in FIG. 7. Subsequently, at 33 counted pulses
(approximately 5 inches), the timer 56b begins counting a 3.5 second
delay. Between 33 and 39 PFS pulses, the control routine monitors the
perforation/fold signal PERF (in the example of FIG. 6, indicating the
first detectable fold being "outside," and leading fold "inside"). Between
99 and 105 the control routine monitors the PFS counter (HSC) to check for
a third subsequent fold (in the example of FIG. 6, no detection is
recorded since the third fold is "inside").
Following a 3.5 second delay, the motor 22 is started in the
counterclockwise direction (to move the rotatable guide wires 28F, 28R
toward the position shown in FIG. 8A). The motor 22 is stopped upon the
detection of the home signal (HOME), the rotatable guide wires 28F, 28R
stopping at the position shown in FIG. 8A (or 8B). At 165 PFS pulses, the
motor 22 is started in the clockwise direction (reversed), to move the
rotatable guide wires 28F, 28R toward the position shown in FIG. 9. It
should be noted that an error is generated between 165 and 195 PFS pulses
when no "outside" folds, or when two "outside" folds are detected (in the
example of FIG. 6, no error is generated). Between 165 and 195 PFS pulses,
action to stop the motor 22 on a detection of the home signal (HOME) is
suppressed, i.e., ignored by the controller 56. After 195 PFS pulses,
action to stop the motor 22 upon the home signal (HOME) detection is
reactivated. When the home signal is detected for the first time after 195
PFS pulses, the rotation of the motor 22 is stopped, stopping the
rotatable guide wires 28F, 28R at the position shown in FIG. 9.
At 226 PFS pulses, the motor 22 is started in the counterclockwise
direction, to move the rotatable guide wires 28F, 28R to return to the
home position shown in FIG. 7. After 230 PFS pulses the control routine
ends the process, stopping the rotatable guide wires 28F, 28R at the home
position shown in FIG. 7 upon a detection of the home position signal
(HOME).
FIGS. 10A and 10B show a flowchart describing a control routine by which
the leading edge directing system may be controlled, substantially
corresponding to the timing chart shown in FIG. 6, but including steps to
handle both "outside" and "inside" leading and/or detectable folds. The
control routine shown in FIGS. 10A and 10B starts once printing has begun,
and once the leading edge directing system has been activated. As
described, timing for detection locations/intervals for controlling the
laying of the first and/or subsequent sheet(s) may be arranged according
to relaxed ranges (rather than exact values) and the system may therefore
handle various types of forms having various characteristics.
As shown in FIGS. 10A and 10B, once printing has begun, control loops at
step S88 until the top of form sensor (TOF) detects the leading edge of a
pre-folded continuous form along the paper path. Once the top of form
sensor 58 (TOF) detects the presence of a continuous form (i.e., the
leading edge of a continuous form) in the paper path, the PFS counter
(corresponding to HSC in FIG. 6 and/or counter 56a) is begun at step S90.
As previously described, in this embodiment, the PFS counter counts 1/6"
pulses, i.e., 1/6 inch advances of the (e.g., 11 inch sheet) continuous
form according to the PFS sensor 59, e.g., an encoder wheel arranged to
output a pulse for each 1/6" advance of the feeding device (tractor or
rollers, not shown) of the printer 72.
Subsequently, in step S92 the PFS counter is monitored until a count of 33
is reached. In the present embodiment, for the parameters described above
(here, for an 11 inch sheet), the first detectable fold ("outside" or
"inside") may be expected following the leading edge in the range between
33 and 39 PFS pulses, i.e, a PFS count of 33 indicates that a first
detectable fold (perforation) following the leading edge has reached the
region in which the perforation or fold may be detected. Accordingly, when
the PFS pulse is greater than 32, the timer 56b in the controller 56 is
started. Subsequently, at step S96, the controller 56 checks if the PFS
pulse count is still less than 39. If the PFS pulse is less than 39 in
step S96, control continues to step S98, in which the control routine
checks if a perforation has been detected. It should be noted that in this
embodiment, the fold detector 57 detects only one direction of fold cusp,
e.g., an "outside" fold. If an "outside" fold is detected at step S98,
signifying that an "outside" fold has been detected in the range between
33 and 39 PFS pulses, then a direction variable (DIR) is set to 1 in step
S102, indicating that the first direction of rotation of the rotatable
guide motor 46 should place the leading edge to the rear of the horizontal
stacking support assembly 14 and the leading fold to the front, i.e.,
indicating that the front guide wire 28F is to be rotated in a clockwise
direction from the perspective of FIG. 1. The control routine further sets
a flag "FU" to equal one, indicating that the first detected fold is
"outside" (or "up") at step S102. Control then loops at step S103 until
the PFS pulse counter (HSC) exceeds 98, indicating that the second
detectable fold (the third fold following the leading edge) has entered
the region where it may be detected. Subsequently, control continues to
step S104.
If the fold is not detected (as "outside") between 33 and 39 PFS pulses,
the control routine loops between steps S96 and S98 until the PFS pulse
counter (HSC) exceeds 39. When the PFS pulse counter exceeds 39, control
continues to step S101, in which the direction variable (DIR) is set to
-1, indicating that the leading edge of the continuous form should be
placed at the front of the horizontal stacking support assembly 14. In
this context, when a perforation/fold detector 57 only detects one
direction of fold (e.g., outside "O"), the first "detectable" fold may be
an "inside" fold, not directly detected, but detected by the absence of an
"outside" fold at the expected position. Control then loops at step S103
until the PFS pulse counter (HSC) exceeds 98, indicating that the second
detectable fold (the third fold following the leading edge) has entered
the region where it may be detected. Subsequently, control proceeds to
step S104.
Steps S104-S107 monitor whether or not a fold is detected between the third
and fourth sheets (the second detectable fold), i.e., before the PFS
counter reaches 105. In the present embodiment, while the PFS counter
(HSC) is in the range between 99 and 105, two 11 inch sheets have passed
the fold detector 57, and the second detectable fold after the leading
edge of the continuous form (third fold following the leading edge) has
reached the region in which a fold may be detected. As described above,
before the PFS counter (HSC) reaches 105, the control routine has looped
until the PFS counter (HSC) reaches 99 (at step S103). Subsequently, the
control routine loops between steps S104 and S106 until the PFS counter
(HSC) exceeds 106 or a fold is detected. The controller 56 checks if a
fold has been detected (an "outside" fold) at step S106. If a fold is
detected, the control routine proceeds to step S107 where a fold down (FD)
flag is set to 1, indicating that the first detectable fold following the
leading edge of the continuous form is an "inside" fold (necessarily so
since the second detectable fold is an "outside" fold). Otherwise, the
control routine loops until the PFS counter (HSC) exceeds 106, in which
case control proceeds to step S108.
At step S108, the timer 56b is monitored to check if it exceeds 3.5
seconds. A delay of 3.5 seconds is set from when the timer starts at a PFS
count of 33, representing the time taken for a continuous form 74 to pass
from the detection positions of the top of form sensor 58 and the fold
sensor 57 to a predetermined position, i.e., representing the position of
the pre-folded continuous form at which the leading edge directing
mechanism should be initiated. In the present embodiment, this position is
reached when the leading edge of the continuous form is within the entry
path between the front and rear wire guides 28F, 28R, and timed
approximately such that the wire guides 28F, 28R are moved into position
just as the continuous form reaches the end of the wire guides 28F, 28R.
However, it should be noted that the delay may be shortened or lengthened
based on, for example, the length or stiffness of a form. Furthermore, the
delay may be shortened such that the appropriate one of the front and rear
guide wires 28F, 28R is swung into position before the continuous form 74
actually enters the region of the transport path passing between the
rotatable guide wires 28F, 28R.
When the timer exceeds 3.5 seconds, control proceeds to step S110. At step
S110, the motor is turned ON in the direction previously set in the
direction variable DIR (1 or -1). That is, in step S110, if the variable
DIR was set to 1 at step S102, the rotatable guide motor 22 is started by
the controller 56 in the appropriate direction (counterclockwise from the
perspective of FIG. 1) to place the leading edge of the form at the rear
of the horizontal stacking support assembly 14. In other words, the
rotatable guide motor 22 is started to move the front and rear rotatable
guide wires 28F, 28R towards the position shown in FIG. 8A, in which the
rotatable guide wires 28F, 28R are rotated from the home position by
approximately 90.degree. toward the rear of the horizontal stacking
support assembly 14. That is, the drive motor 22 is rotated for one full
revolution (in the counterclockwise direction from the perspective of FIG.
1) until the home position is detected.
Conversely, at step S110, if the variable DIR was set to -1 in step S101,
then the rotatable guide motor 22 is started by the controller 56 in the
appropriate direction (clockwise from the perspective of FIG. 1) to place
the leading edge of the continuous form at the front of the horizontal
stacking support assembly 14. That is, the motor 22 is started to rotate
the front and rear rotatable guide wires 28F, 28R by approximately
90.degree. toward the front of the horizontal stacking support assembly
14. In other words, the motor 22 is started to rotate the front and rear
rotatable guide wires 28F, 28R toward positions left-right mirrored with
respect to the positions shown in FIG. 8A.
Accordingly, when the first detectable fold following the leading edge of
the continuous form is an "outside" fold (i.e., with the fold cusp
pointing upward), the leading fold is therefore an "inside" fold, the
leading edge of the pre-folded continuous form is placed toward the rear
of the horizontal stacking support assembly 14, and the top surface of the
continuous form is laid down at the front of the horizontal stacking
support assembly 14. In this manner, the leading fold may be folded over
at the front of the horizontal stacking support assembly 14. Conversely,
when the first detectable fold following the leading edge of the
continuous form is an "inside" fold (i.e., with the fold cusp pointing
down, as indicated by, e.g., a detection of the second detectable fold as
"outside") the leading edge is placed toward the front of the horizontal
stacking support assembly 14, and the bottom surface of the continuous
form is laid down toward the rear of the horizontal stacking support
assembly 14. In this manner, the leading fold may fold over at the rear of
the horizontal stacking support assembly 14.
Subsequently, control passes to step S114, at which the PFS counter (HSC)
is checked again. Steps S114, S116, S112, and S113 form a routine for
error checking and for suppressing the result of the position sensor 54
during a second (reversing) rotation of the motor 22 in the opposite
direction to the first rotation. In this respect, during the first
rotation after step S108, the PFS counter is less than 165 and the control
routine passes without branching through step S114 to step S118.
Accordingly, steps S112-S116 are described in detail below in association
with the second, reversing rotation.
When control passes to step S118 on the first rotation, the controller 56
checks if the drive gear 22b has passed through one full revolution by
detection of the home position via the position sensor 54, and returns to
step S114 if the home position is not detected. When the drive gear 22b
has completed one full revolution (when the position sensor 54 detects the
home position on the encoder wheel 52), each of the driven gears 24F and
24R and corresponding rotatable guide wires 28F and 28R have turned
through one-quarter revolution, or approximately 90.degree.. Accordingly,
the control routine loops between steps S114 and S118 until the sensor 54
detects the home position of the encoder wheel 52. When the home position
has been detected, control proceeds to step S120, in which the rotatable
guide drive motor 22 is turned OFF.
Subsequently, control passes to step S122, in which the direction variable
DIR is reversed. That is, the direction variable DIR is made -1 if
previously 1, and is made 1 if previously -1. Accordingly, the next time
the motor 22 is started in step S110 according to the direction variable
DIR and following an execution of step S122, the rotation direction is
reversed from the previous rotation.
Control then passes to step S124, at which the controller checks if the
routine has ended by detecting if the PFS counter (HSC) has reached 230.
This step is the final step that exits the routine, and therefore, after
the first rotation and second (reversing) rotations of the motor 22, the
PFS counter has not yet reached 230. Accordingly, on the first two passes
through step S124, control proceeds through step S124 to step S128, at
which point the control routine loops until the PFS counter reaches 165.
The third pass through step S124 is described below.
At 165 PFS pulses, the front sheet has been laid appropriately (to the
front or rear) in the horizontal stacking support assembly 14, and the
second sheet is to be directed to lay down the leading fold between the
first and second sheets of the continuous form appropriately. Control
passes to step S127, which checks whether the PFS pulse counter is greater
than 195, indicating that the second rotation of the motor 22 has passed
at least the midpoint. Since the PFS counter has not reached 195
immediately after the first rotation and verification of 165 PFS pulses at
step S128, step S127 directs the control routine to step S110 at this
point. That is, after the first rotation, but before the second, reversing
rotation has begun, control proceeds from step S127 to step S110.
At step S110, the motor 22 is again turned ON, but in the opposite
direction (via step S122) to which the motor 22 is turned ON in the first
rotation. On the second (reversing) rotation, at step S114, the PFS
counter (HSC) is greater than 165 (having looped at step S128), and
control passes to step S116 to check if the PFS counter has reached 195
(signifying that the second rotation of two revolutions has completed one
revolution, but not two revolutions).
Between the PFS count pulse values of 165 and 195, the control routine
checks to see if either two "outside" folds were detected or whether no
"outside" folds were detected (according to the settings of flags FU
and/or FD at steps S98 and S106). Accordingly, in step S112, an exclusive
OR (XOR) operation is performed on the FU and FD flags. If a zero is
returned, signifying that two "outside" folds were detected or that no
"outside" folds were detected (in the ranges at 33-39 PFS pulses and
99-105 PFS pulses), an error is generated and the control routine stops
the motor 22 at step S113.
If only one fold, i.e., if an "outside" fold was detected at either the
33-39 PFS pulse range (FU flag) or the 99-105 PFS pulse range (FD flag),
control loops between steps S114, S116, and S112 until the PFS pulse
counter equals 195, at which point control passes from step S116 to step
S118. That is, in the range between 165 and 195 PFS pulses, the result of
the position sensor 54 is suppressed, i.e., the result is ignored by the
controller 56, so that the motor 22 may make two full revolutions during
the second rotation to move the rotatable guide wires 28F and 28R between
the position shown in FIG. 8A to that shown in FIG. 9 (or left-right
mirrored positions, depending on the orientation of the first detectable
fold). That is, in the range between 165 and 196 PFS pulses, the position
sensor 54 outputs a signal indicating the home position of the encoder
wheel 52, i.e., indicating that each of the rotatable guide wires 28F and
28R has returned to the home position. However, since the control routine
loops between steps S114, S116 and S112 in the 165-195 PFS pulse count
range, no action based on the home position signal is taken by the
controller 56 in the 165-195 PFS pulse count range.
However, when the controller 56 checks the PFS pulse counter at step S116
and determines that the PFS count is equal to (or greater than) 195,
control proceeds to step S118. That is, toward the end of the second
revolution of the second (reversed) rotation, the controller 56 again
monitors the position sensor 54, and proceeds to step S120 when a full
revolution of the encoder wheel 52 (corresponding to drive gear 22b) is
detected, otherwise looping through steps S118, S114, and S116. When the
controller 56 detects the home position for the first time after 195 PFS
pulses, the drive gear 22b has turned by two revolutions from the previous
stopped position (following the first rotation). Accordingly, during the
second (reverse) rotation, and after 195 PFS pulses have been counted,
when the encoder wheel 52 is detected at the home position (at step S118),
control passes to step S120.
At step S120, the motor 22 is again turned OFF. At this point, for a first
detected "outside" fold, the rotatable guide wires 28F and 28R are in the
position shown in FIG. 9, as is the continuous form 74. However, if the
first detected fold was an "inside" fold, then the rotatable guide wires
28F and 28R are in a position left-right mirrored with respect to the
position shown in FIG. 9.
The control routine then proceeds to step S122. At step S122 the direction
variable DIR is again reversed (-1 becoming 1, 1 becoming -1) to prepare
for the return of the rotatable guides 28F and 28R to the home position in
a third (home return) rotation. Control then passes through steps S124
(since the PFS counter HSC has not yet reached 230), S128 (since the PFS
counter HSC exceeds 165), and S127 (since the PFS counter HSC exceeds
195).
At step S126, the control routine loops until the PFS counter HSC is
greater than 225. At 225 PFS pulses, the leading sheet, leading fold, and
the second sheet have been laid appropriately in the horizontal stacking
support assembly 14. Accordingly, the front and rear rotatable wire guides
28F and 28R are to be directed to return to the home position shown in
FIG. 7 such that the wire guides 28F, 28R do not interfere with subsequent
stacking. Accordingly, at step S126, when the PFS counter exceeds 225, the
control routine returns to step S110.
On the third (home return) rotation at step S110, the motor 22 is turned
ON, now in the appropriate direction to return the rotatable guide wires
28F and 28R to their home position. The control routine again loops
through steps S114, S116 and S118 until the home position is again
detected at step S118, upon which the motor is turned OFF at step S120.
The direction variable DIR is then reversed at step S122 (which has no
further effect), and the control routine then proceeds to step S124. At
step S124, after the third (home return) rotation, the PFS counter is
greater than 230, (being approximately 250 after the third rotation) at
which point the process ends.
When the process ends, printing may continue, and the continuous form
continues to stack correctly on the horizontal stacking support assembly
14, at least the leading sheets, leading fold, and second sheet having
been laid correctly on the horizontal stacking support assembly 14. The
stacking may be assisted by the active stacking mechanism 76, as
previously described.
FIG. 11 shows a flow chart describing a routine in which the delays and
intervals are adjusted dynamically in response to changing sheet feed
rates. This routine may be performed by the controller 56 concurrently
with the previously described operation process. Accordingly, if the feed
rate changes for any reason, e.g., if the printer 72 prints a page having
a large image or graphic requiring significant processing, the delays and
timing may be adjusted to compensate (e.g., by monitoring the PFS sensor
59, as shown in FIG. 11).
FIG. 12 shows a second embodiment of the leading edge directing system, in
which a perforation/fold detector 57' is placed within the printer 72. In
such a case, the controller 56 of the leading edge directing system may be
incorporated in the controller of the printer 72. To accomplish
appropriate timing and control for the second embodiment, the delays and
intervals previously described are adjusted for the new distances between
the perforation/fold sensor 57' and the TOF sensor 58 (e.g., being
substantially the same if the perforation/fold sensor 57' is advanced by
length of a sheet toward the TOF sensor 58). In addition, if the new
position of the perforation/fold sensor 57 is such that the first
detectable fold is now the leading fold, then the settings (1 or -1) of
the direction variable DIR would be reversed from those described.
Otherwise, the operation of the second embodiment is essentially similar
to that described for the first embodiment.
FIGS. 13A, 13B, 14A, and 14B show a first embodiment of a fold detector 60,
suitable for use as the previously described fold/perforation detector
57'. In each case, the fold detector 60 detects outside folds "O" of a
form 74 having alternating inside folds "I" and outside folds "0." That
is, a media stack 74a is conventionally folded back upon itself in
accordion-fashion, and as each sheet of the form 74 is drawn from the
media stack 74a, the successive sheets are separated by alternating inside
folds "I" and outside folds "O." As previously described, an "outside"
fold "0" is one that enters the printer with the fold cusp pointing
upward, and an "inside" fold "I" is one that enters the printer with the
fold cusp pointing downward.
FIG. 13A shows the continuous form 74 along a transport path from the media
stack 74a before a fold is detected, and FIG. 13B shows the continuous
form 74 along the transport path as a fold (an outside fold "O") is
detected. As shown in FIGS. 13A and 13B, the first embodiment of a fold
detector 60 relies on observed characteristics (e.g., the fold memory and
normal stiffness properties) of a pre-folded continuous form 74 as the
form 74 passes over a corner 60a. In the context of this specification, a
"corner" may be an angled, square, or rounded corner.
Upstream of the printer (not shown in FIGS. 13A, etc., but positioned
downstream of the fold detector 60 along the transport path), the form 74
is only under the tension imparted to the form by the weight of the form
74 as it is drawn from the media stack 74a. The tension imparted by the
weight of the form, i.e., gravity, is low, i.e., the weight of, at most, a
few sheets of the form 74. Accordingly, although the present embodiment
operates under tension imparted by the weight of one or more sheets, a
tension of substantially the same or a similar amount may be imparted by
known mechanical means (rollers, etc.).
As shown in FIGS. 13A and 13B, under the low tension imparted by the weight
of the hanging form 74, the folds (either inside folds "I" or outside
folds "O") in the form 74 do not completely straighten when drawn from the
media stack 74a. Instead, the folds assume a typical shape as shown in
FIGS. 13A and 13B, each fold forming a cusp in the form 74a.
As shown in FIG. 13A, when the transport path is, e.g., substantially
straight for a portion downstream of the corner 60a, and the form 74
assumes a rounded shape passing over the corner 60a as it hangs down to
the media stack 74a. The hanging portion of the form 74 is curved or
rounded under cantilever action by the inherent stiffness of the form 74
and the tension (e.g., from the weight of the form 74) on the hanging
portion of the form 74. That is, the corner 60a changes the direction of
the continuous form 74, and due to the stiffness of the form 74, forms a
detectable clearance between a wall of the corner 60a and the form 74.
This rounded shape exists when either an unfolded portion of the form 74
or an inside fold "I" passes over the corner 60a.
However, as shown in FIG. 13B, when an outside fold "O" reaches the corner
60a, the form 74 moves toward, and finally contacts a wall (in FIG. 13B, a
vertical wall) of the corner 60a. The motion and change in position and
direction of the form 74 may be detected as described hereinafter. That
is, since the outside fold "O" bends in the same direction as the corner
60a, the detectable clearance between a wall of the corner 60a and the
form 74 is reduced.
FIGS. 14A and 14B show the fold detector 60 in detail in the same
conditions as FIGS. 13A and 13B, respectively. As shown in FIGS. 14A and
14B, the detector 60 includes a downstream wall 61a (e.g., a horizontal
wall) and a detection wall 61b (e.g., a vertical wall) that intersect to
form an angled corner 60a, with an opening 62 formed in the detection wall
61b. A media detection switch 63 (in this case, a limit switch) faces the
detection wall 61b. The media detection switch 63 includes a plunger 65,
and a resilient lever 64 of the media detection switch 63 protrudes
through the opening 62. Although the detection wall 61b is shown as
vertical and at a right angle to the downstream wall 61a in this
embodiment, the detection wall 61b may be inclined to the downstream wall
61a, although it is necessary that a sufficiently large detection
clearance may be formed between a hanging arc 74b and the detection wall
61b as described below.
As shown in FIG. 14A, when the transport path is, e.g., substantially
straight downstream of the corner 60a along the downstream wall 61a, and
an unfolded portion of the form 74 (or an inside fold "I") passes over the
corner 60a, the form 74 assumes a rounded shape passing over the corner
60a. A hanging arc 74b of the form is rounded under cantilever action by
the inherent stiffness of the form 74 and the tension (e.g., from the
weight of the form 74) on the hanging portion of the form 74. A gap is
formed between the hanging arc 74b and the detection wall 61b. That is,
the corner 60a changes the direction of the continuous form 74, and due to
the stiffness of the form 74, forms a detectable clearance between the
detection wall 61b of the angled corner 60a and the form 74. The resilient
lever 64 of the media detection switch 63 extends into the detectable
clearance, but the form 74 does not contact the resilient lever 64. That
is, the media detection switch 63 is responsive to the detectable
clearance, and more particularly, is responsive to the reduction of the
detectable clearance.
However, as shown in FIG. 14B, when an outside fold "O" reaches the corner
60a, since the outside fold "O" bends in the same direction as the corner
60a, the detectable clearance between the detection wall 61b and the form
74 is reduced as the form 74 moves toward the detection wall 61b. The form
74 contacts the resilient lever 64 of the media detection switch 63, and
moves the resilient lever 64 of the limit switch such that the plunger 65
of the media detection switch 63 is depressed. Accordingly, the reduction
of the detectable clearance by the corner 60a activates the media
detection switch 63 and thereby signals the detection of a fold (an
outside fold "O"). Subsequently, as the outside fold "O" passes over the
corner 60a, the form 74 again develops the rounded shape shown in FIG.
14A, and the resilient lever 64 is released as it resiliently returns to
the position shown in FIG. 14A (extending into the gap under the hanging
arc 74b). In this manner, the fold detector 60 may detect all successive
outside folds "O" passing over the detector 60.
The media detection switch 63 may be, but is not limited to, an
optoelectronic interrupt switch, a snap action switch, a reflective object
switch, a pneumatic proximity sensor, or an optoelectronic proximity
sensor. The switch 63 may be of ON-OFF type, of graduated output, or
waveform-generating. The (signal waveform-generating) switch 68 of the
second embodiment of a fold-detector 60' (described below) may be used in
place of the (ON-OFF) limit switch 63 in the first embodiment of a fold
detector 60.
FIGS. 15A, 15B, 16A, 16B, 17A, and 17B show a second embodiment of a fold
detector 60', suitable for use as the previously described
fold/perforation detector 57'. In each case, the fold detector 60' detects
at least outside folds "O" of a form 74 having alternating inside folds
"I" and outside folds "O."FIG. 15A shows the continuous form 74 along a
transport path from the media stack 74a before a fold is detected, and
FIG. 15B shows the continuous form 74 along the transport path as a fold
(an outside fold "O") is detected. As shown in FIGS. 15A and 15B, the
second embodiment of a fold detector 60 relies on observed characteristics
(e.g., the fold memory and normal stiffness properties) of a pre-folded
continuous form 74 as the form 74 passes over an arcuate corner 66 (e.g.,
a curved guide).
As shown in FIGS. 15A and 15B, the form 74 is only under the tension
imparted to the form by the weight of the form 74 as it is drawn from the
media stack 74a, similarly to that previously described with respect to
FIGS. 13A through 14B. Again, under the low tension imparted by the weight
of the hanging form 74, the folds in the form 74 do not completely
straighten when lifted from the media stack 74a, each fold forming a cusp
as shown in FIGS. 15A and 15B. That is, the arcuate corner 66 changes the
direction of the continuous form 74, and due to the stiffness of the
inside or outside fold "I" or "O", forms a detectable clearance between
the wall of the arcuate corner 66 and the form 74.
As shown in FIG. 15A, when the transport path is, e.g., substantially
straight downstream of the arcuate corner 66, and the form 74 hangs down
to the media stack 74a, the form 74 assumes an overall rounded shape along
the arcuate corner 66. This overall rounded shape exists when an unfolded
portion of the form 74, an inside fold "I," or an outside fold "0" passes
along the arcuate corner 66.
However, as shown in FIG. 15B, when an outside fold "O" reaches the arcuate
corner 66, the overall rounded shape is interrupted by the cusp of the
fold "O" remaining in the form 74, the cusp pointing away from the arcuate
corner 66. That is, the arcuate corner 66 changes the direction of the
continuous form 74, and due to the stiffness of the outside fold "O" in
the form 74, forms a detectable clearance between the arctuate corner 66
and the outside fold "O" in the form 74. The detectable clearance may be
detected as described hereinafter.
FIGS. 16A shows the fold detector 60' in detail when an inside fold "I"
passes over the fold detector 60', and FIG. 16B shows the fold detector
60' in detail in the same condition as FIG. 15B, i.e., when an outside
fold "O" passes over the fold detector 60'. As shown in FIGS. 16A and 16B,
the detector 60' includes an arcuate corner 66 (e.g., curving from a
horizontal direction to a vertical direction), with an opening 67 formed
in the arcuate corner 66. A media detection (proximity) switch 68 faces
the opening 67 formed in the arcuate corner 66. That is, the media
detection (proximity) switch 68 is responsive to the detectable clearance,
and more particularly, is responsive to the formation of the detectable
clearance.
As shown in FIG. 16A, when an inside fold "I" of the form 74 passes over
the arcuate corner 66, the form 74 assumes a generally rounded shape
passing over the arcuate corner 66, with the cusp of the inside fold "I"
pointing toward the arcuate corner 66 and toward the media detection
(proximity) switch 68. FIG. 17A shows a signal generated by the media
detection switch 68 as the inside fold "I" passes. In this respect, since
the curves of the cusp of the inside fold "I" curve toward the arcuate
corner 66 and the media detection (proximity) switch 68, as shown in FIG.
16A, the media detection (proximity) switch 68 senses, e.g., two local
minima and a maxima therebetween, as shown in FIG. 17A. If a threshold
level (peak-to-peak or otherwise) is set for detection of a fold (e.g., as
shown by the dashed line in FIG. 17A), the signal generated by an inside
fold "I" will lie below the threshold, and be treated the same as no fold.
That is, the arcuate corner 66 changes the direction of the continuous
form 74 in the same direction as the curves as the cusp of the inside fold
"I", the clearance between the arcuate corner 66 and the inside fold "I"
in the form 74 is minimally changed.
The threshold level may be set, e.g., in the media detection (proximity)
switch 68 itself or in a controller attached thereto (not shown in FIGS.
16A and 16B, but preferably a configuration such as that shown in FIG. 5
with respect to controller 56 and perforation/fold detector 57). If a
threshold level is set in this manner, the media detection (proximity)
switch 68 is not activated by an inside fold "I." Alternatively, the
signal may be recognized as that of an inside fold "I" by the distribution
of maxima and minimum.
As shown in FIG. 16B, when an outside fold "O" of the form 74 passes over
the arcuate corner 66, the form 74 assumes a generally rounded shape
passing over the arcuate corner 66, with the cusp of the outside fold "O"
pointing away from the arcuate corner 66 and away from the media detection
(proximity) switch 68. FIG. 17B shows a signal generated by the media
detection (proximity) switch 68 as the outside fold "O" passes switch 68.
In this respect, since the curves of the cusp of the outside fold "O"
curve away from the arcuate corner 66 and the media detection (proximity)
switch 68, as shown in FIG. 16B, a signal generated by the media detection
(proximity) switch 68 has a minimum, as shown in FIG. 17B. If a threshold
level (peak-to-peak or otherwise) is set for detection of a fold (e.g., as
shown by the dashed line in FIG. 17B), the signal generated by an outside
fold "O" falls below the threshold, and is detected as a fold. That is,
the media detection (proximity) switch 68 is responsive to the formation
of the detectable clearance of the outside fold "O" of the form 74.
Alternatively, the signal may be recognized as that of an outside fold "O"
by the distribution of minimum and flat portions of the curve.
Subsequently, as the outside fold "O" is transported past the media
detection switch 68 along the arcuate corner 66, the form 74 again follows
the arcuate corner 66 as shown in FIG. 15A, and the signal level of the
media detection (proximity) switch 68 is raised to a baseline or zeroed
value along with the detectable clearance. In this manner, the fold
detector 60' may detect all successive outside folds "O" passing over the
detector 60', or both inside and outside folds "I" and "O" passing over
the detector 60'.
The media detection (proximity) switch 68 may be, but is not limited to, an
optoelectronic interrupt switch, a snap action switch, a reflective object
switch, a pneumatic proximity sensor, or an optoelectronic proximity
sensor. The switch 68 may be of ON-OFF type, of graduated output, or
waveform-generating. The (ON-OFF) switch 63 of the first embodiment of a
fold-detector 60 may be used in place of the waveform-generating switch 68
in the second embodiment of a fold detector 60'.
It should be noted that although each of the first and second embodiments
of a fold detector 60 and 60' uses a minimal tension in the form 74
imparted by the weight of the form, it is not necessary that the form 74
hang down to the media stack 74a. For example, in both cases, the minimal
tension may be generated by rollers, sprockets, or other feeding device,
or by bends or a labyrinth in the continuous form 74 transport or guide
path. Accordingly, the media stack 74a need not be below the detector 60
or 60', but may be at the same height or higher.
Furthermore, although each detector 60 and 60' is shown as positioned at a
junction between a horizontal portion of the form 74 transport path and a
vertical portion of the form 74 transport path (e.g., where the form 74
hangs down toward the media stack 74a), either of the detectors 60 or 60'
may be positioned in the middle of a horizontal, vertical, or inclined
portion of the form 74 transport path, if the profile achieves the
characteristics noted above. That is, it is required that the detector 60
or 60' changes the direction of the form 74, at least temporarily.
For example, the first embodiment of a fold detector 60 requires a
sufficiently long downstream portion (e.g. horizontal wall 61a), coupled
with a detection wall 61b sufficiently angled from the downstream portion,
to form a corner 61 that generates the described gap when a form 74
extends across the two walls 61a and 61b of the corner 61. However, either
of the walls 61a or 61b may be horizontal, inclined, or vertical, and the
corner 61 may be placed in the middle of, or at a junction of, horizontal,
inclined, or vertical portions of the transport path of the form 74.
Similarly, the second embodiment of a fold detector 60' merely requires
that a sufficient length of the form 74 follow an arcuate corner 66; the
arcuate corner 66 need not be of any particular radius, sector amount, or
orientation, and may be placed in the middle of, or at a junction of,
horizontal, inclined, or vertical portions of the transport path of the
form 74.
Furthermore, although placing the fold detector 60 or 60' upstream of the
printer is advantageous (i.e., at the inlet of the printer) because the
folds have not yet been "ironed out" by a fusing unit of the printer, the
fold detector 60 or 60' may be positioned within the printer (e.g., as
shown with respect to sensor 57' in FIG. 12) or downstream of the printer
(i.e., at the outlet of the printer).
As described, the leading edge directing system, including the various
sensors and inputs to the controller 56, can conduct operations in which:
(1) the position(s) of the first and/or subsequent fold(s) and/or leading
edge are detected; (2) the orientation(s) of the first and/or subsequent
fold(s) are detected; (3) the position(s) of first and/or subsequent
fold(s) and/or leading edge are set manually by an operator; (4) the
position(s) of the first and/or subsequent fold(s) and/or leading edge are
determined according to a timer from a predetermined position; (5) the
position(s) of the first and/or subsequent fold(s) and/or leading edge are
determined according to direct measurement of the advance of the
continuous form and/or the feeding device; and/or (6) the continuous form
is set in a predetermined position and the leading edge directing system
is started, including any combinations of these operations.
Various modifications may be made to the system without departing from the
spirit and scope of the invention.
For example, the control system may be arranged to proceed from the
position of FIG. 7 to one of FIGS. 8A or 9, and then to return to FIG. 7,
therefore laying the first sheet only in the appropriate direction. In
such a case, the leading fold and second sheet would be allowed to fall
into position without assistance from the leading edge directing system.
As described, the leading edge directing system according to the invention
appropriately directs leading sheets of a pre-folded continuous form so
that all subsequent folding onto a stack develops correctly. Furthermore,
the leading edge directing system appropriately directs leading sheets of
a continuous form for any orientation of the folds in the pre-folded
continuous form. Since only one guide wire is permitted to contact the
form at any time, timing for detection locations/intervals for controlling
the laying of the first and/or subsequent sheet(s) may be arranged
according to relaxed ranges (rather than exact values) and the system may
therefore handle various types of forms having various characteristics.
Although the above description sets forth particular embodiments of the
present invention, modifications of the invention will be readily apparent
to those skilled in the art, and it is intended that the scope of the
invention be determined by the appended claims.
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